The present invention relates to techniques for improving computer system performance by using a proximity I/O switch to facilitate communication between components within a computer system.
Advances in semiconductor technology presently make it possible to integrate large-scale systems, including tens of millions of transistors, into a single semiconductor chip. Integrating such large-scale systems onto a single semiconductor chip increases the speed at which such systems can operate, because signals between system components do not have to cross chip boundaries, and are not subject to lengthy chip-to-chip propagation delays. Moreover, integrating large-scale systems onto a single semiconductor chip significantly reduces production costs, because fewer semiconductor chips are required to perform a given computational task.
Unfortunately, these advances in semiconductor technology have not been matched by corresponding advances in inter-chip communication technology. Semiconductor chips are typically integrated onto a printed circuit board that contains multiple layers of signal lines for inter-chip communication. However, a semiconductor chip contains about 100 times more signal lines than a printed circuit board. Consequently, only a tiny fraction of the signal lines on a semiconductor chip can be routed across the printed circuit board to other chips. This problem is creating a bottleneck that is expected to worsen as semiconductor integration densities continue to increase.
This bottleneck can adversely affect computer system performance in a number of ways. For example, (1) it can limit the amount of data that can be transferred between processors and memories; (2) it can limit the amount of data that can be transferred between processors and other computer system components, such as peripheral devices and network interfaces; and (3) it can limit the amount of data that can be transferred between processors in a multiprocessor system.